Primary hyperaldosteronism

What it is

Primary hyperaldosteronism, sometimes referred to as Conn syndrome, is an excess of aldosterone caused by autonomous overproduction. It is typically due to adrenal hyperplasia, most commonly bilateral, or an adrenal adenoma, typically unilateral. The pattern is hypertension with a raised sodium and a low potassium.

How it presents

Hypertension is resistant to pharmacotherapy, with hypernatremia, hypokalemia producing headache, muscle weakness and polyuria, and metabolic alkalosis. Further workup is prompted by resistant hypertension, a stroke at less than 40 years of age, a family history of early-onset hypertension or of primary hyperaldosteronism, an adrenal incidentaloma, and possible hypokalemia with consequent metabolic alkalosis. Unprovoked or significant hypokalemia is itself a sign suggestive of secondary hypertension, and hyperaldosteronism is among the most common causes of secondary hypertension between 40 and 64 years of age. On the differential of metabolic alkalosis it belongs to the hypervolemic, high urine chloride, saline-unresponsive group of excess mineralocorticoid activity, alongside Cushing disease and ectopic ACTH production.

Nonsuppressible primary hypersecretion of aldosterone is an underdiagnosed cause of hypertension, and its classic presenting signs are hypertension and hypokalemia, most often as a difficult-to-treat hypertension. The potassium is not always low, though: the serum potassium level may also be normal on presentation, which is how the diagnosis is missed. A worked case is a 60 year old man with hypertension and generalized weakness, a serum potassium of 2.3 mmol/L against a range of 3.5-5.0, a low serum renin and a high serum aldosterone, with a urine potassium excretion of 100 mmol/day in a range of 25-120.

What stands beside it in the differential of hypokalaemia with hypertension is Cushing's syndrome, Liddle's syndrome and 11-beta hydroxylase deficiency, and carbenoxolone, an anti-ulcer drug, and liquorice excess can produce the same pair. Another list for the same pair of hypertension with hypokalemia gives renovascular HTN, that is renal artery stenosis, renin secreting tumors, CAH and Cushing's.